1. Technical Field
The present invention relates to a medium transport apparatus provided with a transport unit which transports a long medium, and a winding unit which winds the medium transported by the transport unit, and to a recording apparatus.
2. Related Art
For example, JP-A-2004-107021 (for example, FIG. 1 or the like) discloses a medium transport apparatus provided with a transport unit (a grip unit) which transports a long recording medium dispatched from a roll-shaped medium (for example, roll paper) loaded in a feed unit to a downstream side while pinching the recording medium between a drive roller and a driven roller (a pinch roller), and a winding unit (a winding scroller) which winds the recording medium transported by the transport unit to the downstream side into a roll shape. A recording apparatus provided with this medium transport apparatus is provided with a recording unit that performs recording (printing) on a portion of the recording medium which is on a medium support portion (a platen) arranged further on the downstream side than the transport unit. After the recording, the recording medium discharged along the paper guide is wound onto the winding unit while tension is applied to the recording medium by a tension roller applying pressure to a portion between the paper guide and the winding unit.
Here, there is a case in which the recording medium is wound onto the winding unit at a position deviated in the width direction in relation to the position at which the recording medium is pinched in the transport unit. In this case, when the biased force during the winding, caused by the winding position in the winding unit deviating in the width direction, propagates to the upstream side, the recording medium in the transport unit deviates in the width direction through the propagated force. This causes the recording medium to skew or meander between the transport unit and the winding unit.
For example, JP-A-2007-245599 (for example, FIG. 5 or the like), JP-A-8-174928 (for example, paragraph 10 or the like) and JP-A-4-270672 (for example, paragraph 10, FIG. 2 or the like) disclose technology in which the friction coefficient of all or part of the peripheral surface of the roller that configures the transport unit (a transport roller or a platen roller) is increased. For example, in JP-A-2007-245599 (for example, FIG. 5 or the like), a friction application member is formed on the transport roller. In addition, in JP-A-8-174928, the surface of a rubber elastic body covering the core material of the platen roller is coated with a fluorine resin, thereby the surface is formed with a friction coefficient value of, for example, 0.4 to 0.6 in relation to the recording medium. In addition, JP-A-4-270672 (for example, paragraph 10, FIG. 2 or the like) provides a belt skew correction unit which includes a correction roller, in which rubber rollers having a relatively large friction coefficient are mounted to both end portions, and functions as a guide roller which applies tension.
However, in the medium transport apparatus of a configuration in which the medium is wound by the winding unit, as in JP-A-2004-107021 (for example, FIG. 1 or the like), in a case in which the medium is wound with a bias, as described above, even if deviation in the width direction of the recording medium is to be suppressed by frictional resistance at a position of the transport unit which is distanced from the winding unit on the upstream side, the portion of the downstream side of the recording medium deviates greatly. Therefore, a very large frictional resistance force is necessary in order to suppress the deviation at the position of the transport unit of the upstream side. Meanwhile, in a case in which the friction coefficient of the roller is significantly increased, there is a concern that the recording medium will jam during transport due to the extremely large frictional resistance force that the recording medium receives from the roller. In a case in which this type of jamming occurs, problems occur, such as the recording medium becoming inclined or the transport position accuracy dropping due to not being able to transport by the necessary transport amount.
Accordingly, as in JP-A-2007-245599 (for example, FIG. 5 or the like), JP-A-8-174928 (for example, paragraph 10 or the like) and JP-A-4-270672 (for example, paragraph 10, FIG. 2 or the like), even if the friction coefficient of all or part of the roller is increased, there is a problem in that it is difficult to sufficiently suppress the skewing or the meandering of the medium between the transport unit and the winding unit, where the skewing or the meandering of the medium is caused by the winding position of the medium in the winding unit being biased in a direction (the width direction) which is perpendicular to the transport direction.